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From: Daniel Phillips <phillips@arcor.de>
To: William Lee Irwin III <wli@holomorphy.com>
Subject: Re: Generic list push/pop
Date: Mon, 19 Aug 2002 14:32:48 +0200
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On Monday 19 August 2002 14:05, William Lee Irwin III wrote:
> On Sun, Aug 18, 2002 at 09:21:41PM +0200, Daniel Phillips wrote:
> > I took a run at writing generic single-linked list push and pop macros, to be 
> > used in the form:
> 
> Dear gawd, I've gone blind.
> 
> How's this look?

Unfortunately, not good.  You get code like:

	foo = (struct mylist *) slist_pop((slist *) &somelist->next);

So type safety goes out the window, and you gain some niceness in the
definition in exchange for ugliness in usage, the wrong tradeoff imho.

> struct slist
> {
> 	struct slist *next;
> };
> 
> 
> static inline void slist_add(struct slist *head, struct slist *elem)
> {
> 	elem->next = head->next;
> 	head->next = elem;
> }
> 
> #define slist_push(head, elem)	slist_add(head, elem)
> 
> static inline struct slist *slist_pop(struct slist *head)
> {
> 	struct slist *elem = head->next;
> 
> 	if (elem) {
> 		head->next = elem->next;
> 		elem->next = NULL;
> 	}
> 	return elem;
> }

-- 
Daniel
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